Your choices become more interesting if you are running a small cluster or a big server farm. Under those circumstances, it may not be possible or even desirable to pair a UPS with every single machine. apcupsd supports some alternate arrangements.
The second type of configuration is the NIS (Network Information Server) server and client. In this configuration, where one UPS powers several computers, a copy of apcupsd running one one computer will act as a server while the other(s) will act as network clients which poll the server for information about the UPS. Note that ``NIS" is not related to Sun's directory service also called ``NIS" or ``Yellow Pages''.
The third configuration (new with version 3.8.3), is where a single computer controls multiple UPSes. In this case, there are several copies of apcupsd on the same computer, each controlling a different UPS. One copy of apcupsd will run in standalone mode, and the other copy or copies will normally run in master/slave mode. This type of configuration may be appropriate for large server farms that use one dedicated machine for monitoring and diagnostics
Here is a diagram that summarizes the possibilities:
Configuration types.
If you decide to set up one of these more complex configurations, see the Advanced Topics (see Advanced topics) section for details.